Pipe fitting

Abstract

A pipe fitting is made of plastic, such as polysulphone PSU or polyphenylsulphone PPSU. At least one end of the pipe fitting ( 1 ) comprises an external thread ( 2 ) for connecting the pipe fitting ( 1 ) to a mounting element, such as a pipe or a mounting piece, e.g. a tap. The thread ( 2 ) comprises a ridge ( 3 ). Between the ridges ( 3 ) there is a continuous helical groove ( 4 ). On the bottom of the groove ( 4 ) between the ridges ( 3 ) of the thread ( 2 ) there are protrusions ( 5 ).

1. A pipe fitting, which is made of plastic, intended to act as a connection piece to join at least two mounting elements, comprising
 a thread on at least one end of the pipe fitting, the thread configured to connect the pipe fitting and one of the at least two mounting elements to each other by means of a threaded connection; and 
 a seal on the thread, 
 wherein on the bottom of a groove between ridges of the thread there are protrusions configured to keep the seal in place. 
 
   
   
     2. A pipe fitting as claimed in  claim 1 , wherein the height of the protrusions is 10 to 50% of the height of the ridges. 
   
   
     3. A pipe fitting as claimed in  claim 1 , wherein at the starting end of the thread the bottom of the groove does not comprise protrusions at least at the distance of one pitch. 
   
   
     4. A pipe fitting as claimed in  claim 1 , wherein the protrusions are arranged in the successive grooves in such a manner that the protrusions form ribs. 
   
   
     5. A pipe fitting as claimed in  claim 4 , wherein the protrusions are arranged in the same line with each other in the axial direction such that they form axial ribs. 
   
   
     6. A pipe fitting as claimed in  claim 1 , wherein the thread is arranged at a distance from the end of the pipe fitting in such a manner that the end of the pipe fitting comprises an unthreaded section acting as a guide surface. 
   
   
     7. A pipe fitting as claimed in  claim 6 , wherein the ratio of the length of the unthreaded section to the diameter of the pipe fitting is greater than 1:6. 
   
   
     8. A pipe fitting as claimed in  claim 1 , wherein there are 2 to 24 protrusions at one point around the circumference of the pipe fitting. 
   
   
     9. A pipe fitting as claimed in  claim 1 , wherein the upper surface of each of the protrusions is straight. 
   
   
     10. A pipe fitting as claimed in  claim 2 , wherein at the starting end of the thread the bottom of the groove does not comprise protrusions at least at the distance of one pitch.